<!DOCTYPE html>
<html>
<title>Test that opacity changes on layers make the Compositor repaint the right area</title>

<style>

#box {
  width: 100px;
  height: 100px;
  border: 10px solid black;
  opacity: 1;
  will-change: opacity;
}

#box.halfTransparent {
  opacity: 0.5;
}

</style>

<div id="box" class="halfTransparent"></div>
